Silver nanoparticles from oregano leaves’ extracts as antimicrobial components for non-infected hydrogel contact lenses

The oregano leaves’ extract (ORLE) was used for the formation of silver nanoparticles (AgNPs(ORLE)). ORLE and AgNPs(ORLE) (2 mg/mL) were dispersed in polymer hydrogels to give the pHEMA@ORLE_2 and pHEMA@AgNPs(ORLE)_2 using hydroxyethyl–methacrylate (HEMA). The materials were characterized by X-ray fluorescence (XRF) spectroscopy, X-ray powder diffraction analysis (XRPD), thermogravimetric differential thermal analysis (TG-DTA), derivative thermogravimetry/differential scanning calorimetry (DTG/DSC), ultraviolet (UV-Vis), and attenuated total reflection mode (ATR-FTIR) spectroscopies in solid state and UV–Vis in solution. The crystallite size value, analyzed with XRPD, was determined at 20 nm. The antimicrobial activity of the materials was investigated against Gram-negative bacterial strains Pseudomonas aeruginosa (P. aeruginosa) and Escherichia coli (E. coli). The Gram-positive ones of the genus of Staphylococcus epidermidis (S. epidermidis) and Staphylococcus aureus (S. aureus) are known to be involved in microbial keratitis by the means of inhibitory zone (IZ), minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC). The IZs, which developed upon incubation of P. aeruginosa, E. coli, S. epidermidis, and S. aureus with paper discs soaked in 2 mg/mL of AgNPs(ORLE), were 11.7 ± 0.7, 13.5 ± 1.9, 12.7 ± 1.7, and 14.3 ± 1.7 mm. When the same dose of ORLE was administrated, the IZs were 10.2 ± 0.7, 9.2 ± 0.5, 9.0 ± 0.0, and 9.0 ± 0.0 mm. The percent of bacterial viability when they were incubated over the polymeric hydrogel discs of pHEMA@AgNPs(ORLE)_2 was interestingly low (66.5, 88.3, 77.7, and 59.6%, respectively, against of P. aeruginosa, E. coli, S. epidermidis, and S. aureus) and those of pHEMA@ORLE_2 were 89.3, 88.1, 92.8, and 84.6%, respectively. Consequently, pHEMA@AgNPs(ORLE)_2 could be an efficient candidate toward the development of non-infectious contact lenses

Hydrogels containing water soluble conjugates of silver(i) ions with amino acids, metabolites or natural products for non infectious contact lenses

The poor handling and hygiene practices of contact lenses are the key reasons for their frequent contamination, and are responsible for developing ocular complications, such as microbial keratitis (MK). Thus there is a strong demand for the development of biomaterials of which contact lenses are made, combined with antimicrobial agents. For this purpose, the known water soluble silver(i) covalent polymers of glycine (GlyH), urea (U) and the salicylic acid (SalH2) of formulae [Ag3(Gly)2NO3]n(AGGLY), [Ag(U)NO3]n(AGU), and dimeric [Ag(salH)]2(AGSAL) were used. Water solutions ofAGGLY,AGUandAGSALwere dispersed in polymeric hydrogels using hydroxyethyl-methacrylate (HEMA) to form the biomaterialspHEMA@AGGLY-2,pHEMA@AGU-2, andpHEMA@AGSAL-2. The biomaterials were characterized by X-ray fluorescence (XRF) spectroscopy, thermogravimetric differential thermal analysis (TG-DTA), differential scanning calorimetry (DTG/DSC), attenuated total reflection spectroscopy (FT-IR-ATR) and single crystal diffraction analysis. The antibacterial activity ofAGGLY,AGU,AGSAL,pHEMA@AGGLY-2,pHEMA@AGU-2andpHEMA@AGSAL-2was evaluated against the Gram negative speciesPseudomonas aeruginosa(P. aeruginosa) and Gram positive onesStaphylococcus epidermidis(S. epidermidis) andStaphylococcus aureus(S. aureus), which mainly colonize in contact lenses. Thein vitrotoxicity of the biomaterials and their ingredients was evaluated against normal human corneal epithelial cells (HCECs) whereas thein vitrogenotoxicity was evaluated by the micronucleus (MN) assay in HCECs. TheArtemia salinaandAllium cepamodels were applied for the evaluation ofin vivotoxicity and genotoxicity of the materials. Following our studies, the new biomaterialspHEMA@AGGLY-2,pHEMA@AGU-2, andpHEMA@AGSAL-2are suggested as efficient candidates for the development of antimicrobial contact lenses. © The Royal Society of Chemistry 2021

Silver nanoparticles using eucalyptus or willow extracts (AgNPs) as contact lens hydrogel components to reduce the risk of microbial infection

Eucalyptus leaves (ELE) and willow bark (WBE) extracts were utilized towards the formation of silver nanoparticles (AgNPs(ELE), AgNPs(WBE)). AgNPs(ELE) and AgNPs(WBE) were dispersed in polymer hydrogels to create pHEMA@AgNPs(ELE)_2 and pHEMA@AgNPs(WBE)_2 using hydroxyethyl-methacrylate (HEMA). The materials were characterized in a solid state by X-ray fluorescence (XRF) spectroscopy, X-ray powder diffraction analysis (XRPD), thermogravimetric differential thermal analysis (TG-DTA), differential scanning calorimetry (DTG/DSC) and attenuated total reflection spectroscopy (ATR-FTIR) and ultraviolet visible (UV-vis) spectroscopy in solution. The antimicrobial potential of the materials was investigated against the Gram-negative bacterial strain Pseudomonas aeruginosa (P. aeruginosa) and the Gram-positive bacterial strain of the genus Staphylococcus epidermidis (S. epidermidis) and Staphylococcus aureus (S. aureus), which are involved in microbial keratitis. The percentage of bacterial viability of P. aeruginosa and S. epidermidis upon their incubation over the pHEMA@AgNPs(ELE)_2 discs is interestingly low (28.3 and 6.8% respectively), while the inhibition zones (IZ) formed are 12.3 ± 1.7 and 13.2 ± 1.2 mm, respectively. No in vitro toxicity of this material towards human corneal epithelial cells (HCEC) was detected. Despite its low performance against S. aureus, pHEMA@AgNPs(ELE)_2 could be an efficient candidate towards the development of contact lenses that reduces microbial infection risk. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

An Efficient Disinfectant, Composite Material {SLS@[Zn3(CitH)2]} as Ingredient for Development of Sterilized and Non Infectious Contact Lens

The [Zn3(CitH)2] (1) (CitH4= citric acid), was dispersed in sodium lauryl sulphate (SLS) to form the micelle of SLS@[Zn3(CitH)2] (2). This material 2 was incorporated in hydrogel made by hydroxyethyl-methacrylate (HEMA), an ingredient of contact lenses, toward the formation of pHEMA@(SLS@[Zn3(CitH)2]) (3). Samples of 1 and 2 were characterized by UV-Vis, 1H-NMR, FT-IR, FT-Raman, single crystal X-ray crystallography, X-ray fluorescence analysis, atomic absorption and TG/DTA/DSC. The antibacterial activity of 1–3 as well as of SLS against Gram-positive (Staphylococcus epidermidis (St. epidermidis) and Staphylococcus aureus (St. aureus)) and Gram-negative (Pseudomonas aeruginosa (PAO1), and Escherichia coli (E. coli)) bacteria was evaluated by the means of minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and inhibitory zone (IZ). 2 showed 10 to 20-fold higher activity than 1 against the bacteria tested. Moreover the 3 decreases the abundance of Gram-positive microbes up to 30% (St. aureus) and up to 20% (PAO1) the Gram-negative ones. The noteworthy antimicrobial activity of the obtained composite 3 suggests an effective antimicrobial additive for infection-free contact lense

Amantadine copper(II) chloride conjugate with possible implementation in influenza virus inhibition

1-Adamantanamine hydrochloride (AdNH3 + Cl−) is an antiviral drug that is used in the prophylactic or symptomatic treatment of influenza. However, a mutation makes influenza virus, amantadine (AdNH2) resistant. Thus, a new formulation, which combines Cu(II) and amantadine (AdNH2) in one formula [AdNH3 +]·[CuCl3]−, (CA) was developed. CA was characterized by m.p, conductivity measurements, FT-IR and UV–Vis spectroscopies, and X-ray crystallography. To the best of our knowledge the crystal and molecular structure of CA is the first one of amantadine with Cu(II) ions. CA was tested against the A/WSN/33 wt (M2 N31) virus and its mutations M2 S31N, M2 V27A, M2 L26F, M2 A30T and M2 G34E respectively. CA inhibits the wild virus A/WSN/33 wt-M2 N31, and its mutations -M2 S31N, -M2 L26F and -M2 A30T. The inhibition mechanism involves the increased membrane permeability of the CA, than free Cu(II) ions with simultaneous lower toxicity. CA acts by blocking the proton current of A/WSN/33-M2 S31N in a similar manner to Cu(II) ions. In silico studies confirmed that CA can effectively block proton current mediated by -M2 S31N virus replication. Specifically, [CuCl3]− blocks the primary gate of the His37 tetrad which is essential for channel conductance and selectivity. The in vitro toxicity of CA was examined against normal human fetal lung fibroblast (MRC-5) cells. No toxic effect was detected when the MRC-5 cells were treated by CA with concentrations up to 30 μΜ. The absence of micronucleus (MN) in MRC-5 cells treated CA (30 μΜ) confirms the in vitro non genotoxic behavior of the compound. Moreover, no any in vivo toxic effect was detected on Artemia salina upon their treatment with CA at a concentration up to 150 μΜ. © 2020 Elsevier Lt